Method of watermarking a video signal, a system and a data medium for implementing said method, a method of extracting the watermarking from a video signal, and system for implementing said method

Abstract

The method comprises the following steps: applying a watermarking function to motion vectors calculated by estimation of movement between images of a video signal; and generating the watermarked video signal by compensating movement with the aid of the watermarked motion vectors. The watermarking function is applied by: marking the coordinates of the selected motion vector in a space, certain portions of this space constituting a first zone and the other portions of this space constituting a second zone complementary to the first; assigning a binary value to each of the two zones; and where necessary, modifying the coordinates of the selected motion vector so that it is in the zone whose binary value corresponds to a bit of a marking key associated with the selected motion vector.

Description

[0001] The present invention relates to a method of watermarking a video signal, a corresponding system, and a computer readable data medium for storing a signal watermarked by this method. It also relates to a method of extracting the watermarking from a video signal and a system for implementing this method.[0002] To be more precise, the invention relates to a method of watermarking a video signal by applying a watermarking function to motion vectors calculated by motion estimation between images of the video signal, the method being of the type comprising the following steps:[0003] applying the watermarking function to at least some of the calculated motion vectors; and[0004] generating the watermarked video signal by motion compensation with the aid of the watermarked motion vectors,[0005] the watermarking function being applied with the aid of a binary marking key, each bit of which is associated with at least one selected motion vector.[0006] A method of the above kind is desc...

AI Technical Summary

Benefits of technology

[0008] The invention aims to remedy those drawbacks by providing a robust method of watermarking a video signal that improves watermarking performance in terms of invisibility and in which the watermarking is carried by the motion vectors.

[0013] With this approach, greater diversity in the modification of the selected motion vectors can be envisaged, which improves the quality of the watermarking in terms of invisibility. Robustness is also improved since the watermarking leads to modifying the components of the selected motion vectors by a geometrical transformation and not solely by a change of parity.

[0020] The hierarchical approach of this method effectively increases the robustness of watermarking by judiciously spreading the marking key over a plurality of motion vectors, starting from a single selected motion vector.

Problems solved by technology

Unfortunately, that solution is not very robust, since the slightest attack can transform an even ordinate into an odd ordinate and vice-versa.

Moreover, by always modifying the same predetermined component of the selected motion vectors, for example the vertical component, that solution runs the risk of making the watermarking more visible in the video signal.

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